1. Field of the Invention
The present invention relates to a busbar laminate assembly structure to be housed in an electrical connection box, and more specifically to a busbar laminate assembly structure in which a plurality of busbars is assembled in a laminated form under an electrically isolated condition through an insulation plate.
2. Description of the Related Art
An electrical connection box is used for housing electrical equipment containing various electrical circuits and electronic components for automobiles and the like, and is also used as a connection junction for wire harnesses and the like.
Generally, in an electrical connection box, a busbar is housed as a wiring board connected with terminals of various electrical equipment. Such a busbar forms a laminated structure, thereby making it possible to produce complicated wiring.
Below follows a description of the conventional assembly structure of such busbars in reference to FIGS. 5-7. As shown in FIG. 5, a wiring board 40 is formed of first to fourth busbars 1F to 4F formed with certain respective wiring patterns, and first to fourth insulation plates IP1 to IP4 which electrically isolate respective laminates between busbars 1F to 4F.
As shown in FIGS. 5 and 6, respective terminal strips 41 to 44 are bent to a vertical direction (i.e., orthogonal to the busbars and insulation plates) at a predetermined position of respective laminate of busbars 1F to 4F. The length of respective terminal strips 41 and 44 are set so that the strips are positioned of the same height in a laminate assembled condition as described later. Therefore, the terminal strip 41 of the first laminate busbar 1F is set as the shortest terminal strip while the terminal strip 44 of the fourth laminate busbar 4F is the longest terminal strip.
At the position corresponding to the aforementioned respective terminal strips 41 to 44 on the first laminate insulation plate IP1, through-holes 51a to 51d are respectively provided. At the second laminate insulation plate IP2, a fastening hole 52 is provided at a position corresponding to the terminal strip 42, while through-hole 53a and 53b are provided at the positions corresponding to respective terminal strips 43 and 44. At the third laminate insulation plate IP3, a fastening hole 54 is provided at the position corresponding to the terminal strip 43, while a through-hole 55 is provided at the position corresponding to the terminal strip 44. At the fourth laminate insulation plate IP4, a fastening hole 56 is provided at the position corresponding to the terminal strip 44.
The respective through-holes 51a to 51d, 53a, 53b, and 55 are each provided on respective laminate insulation plates IP1 to IP4 form a rectangular hole, with its shorter dimension t2 being greater than the plate thickness t1 for the aforementioned respective terminal strips 41 to 44, thereby making it possible for respectively corresponding terminal strips 41 to 44 to easily be inserted into respective through-holes 51a to 51d, 53a, 53b, and 55. In addition, the fastening hole 52, 54 and 56 form a tapered opening in an inserting direction for receiving respective terminal strips 42 to 44 as shown in FIG. 6. The width of the upper edge of the fastening hole 52, 54, and 56 is narrower than the plate thickness t1 of the respective terminal strips 41 to 44. Terminal strips 42 to 44 can thus be press-fit into respective fastening holes 52, 54, and 56.
As shown in FIG. 6, each laminate of busbars 1F to 4F is assembled in a laminated state, by press-fitting each of the terminal strips 42 to 44 into a respective fastening hole 52, 54 and 55; and by inserting respective terminal strips 41 to 44 into respective corresponding through-holes 51a to 51d, 53a, 53b, and 55. In this case, the lowest portion of the base edge (i.e., the bent portion) 42', 43' and 44' of respective terminal strips 42 to 44 is held and then fastened between the fastening holes 52, 54, and 56, respectively.
It is necessary to bend the terminal strips 41 to 44 in such a manner that each forms a right angle to respective laminate busbars 1F to 4F. Since the bending for terminal strips 41 to 44 is subjected to plastic deformation and retains a slight elastic rebound, there is a limit to the bending accuracy for the respective terminal strips 41 to 44. Therefore, since it is difficult to bend respective terminal strips accurately to the vertical direction (i.e., orthogonal to the busbars), the normal state of terminal strips 41 to 44 has often been slightly obliquely inclined from the vertical direction.
For example, when the terminal strip 44 on tie fourth laminate busbar 4F is bent under a slightly inclined state, as shown in FIG. 7, the terminal strip 44 becomes inclined by an angle .theta. from the original position (i.e., vertical), as illustrated with a two-dot chain line, even when in a laminate assembled condition. This inclination is caused by a shorter dimension t2 of the respective through-holes 51d, 53b, and 55 being set wider than the thickness t1 of the terminal strip 44, thereby contributing to the degree of freedom of the terminal strip 44 that exists in the through-holes 51d, 53b, and 55; and the terminal strip 44 being held and then fastened only on the nearest fastening hole 56 to the bent portion. The terminal strip 44 is thus inclined by angle .theta., the top edge position of terminal strip 44 comes to a position shifted by a distance d from the original position.
Consequently, positioning difficulties have been encountered when mounting a connector, electrical component, and the like on the terminal strip 44. The difficulty of insertion/withdrawal of connectors, electrical components, and the like to the terminal strip becomes greater, thereby causing possible mounting failures.
It is thus desirable to provide a busbar laminate assembly structure capable of maintaining the bending accuracy of the terminal strip bent under the busbar laminate.